Passenger boats along the Usumacinta River wait to take travelers across the Guatemala-Mexico border.

Migration to and through Mexico has been a critical policy issue for the Mexican government since the 1980s, as large numbers of Central Americans have flowed in through the country's porous southern border, first in flight during times of civil war and humanitarian crises and later in pursuit of greater economic opportunity in the United States.

Mexico's responses to the challenges of unauthorized Central American migration have evolved over time, but have often appeared reactive, uncoordinated, and sometimes contradictory. During the early 1990s, the country liberalized access to business and investor visas and created special provisions allowing Guatemalans to enter and work in Mexico's southern border region. At the same time, Mexico tightened access to visas for Central Americans seeking to move beyond the southern border region and created a centralized immigration agency to detain and deport unauthorized migrants.

However, these measures have been ineffective in reducing illegal migration through Mexico, and have been unable to protect Central American transmigrants from abuse and extortion at the hands of both government police forces and organized crime. Official pronouncements in defense of migrants' rights — typically prompted more by concern about the rights of Mexicans in the United States than by the situation of Central Americans in Mexico — contrasted sharply with on-the-ground realities.

Over the past two decades, these contradictions in policy have led to growing calls from Mexican civil society and the international community for Mexico to reform its immigration laws. Part of this was fueled by criticism from the United States that Mexico's own legal framework and treatment of migrants denied it standing to complain about tightening U.S. enforcement and efforts to reduce the size of the Mexican unauthorized population in the United States. The spate of violent and shocking attacks against transiting migrants in 2010 and 2011 at the hands of organized crime groups moved the issue to the top of the Mexican political agenda, and in April 2011 the Mexican Congress unanimously approved a new migration law.

Upon signing the law, Mexican President Felipe Calderón called the reforms the most sweeping changes to Mexican immigration law since the 1974 General Population Law, which primarily focused on the challenges of managing emigration.

The new law is ambitious in scope and sets out to develop a migration policy that respects the human rights of migrants; facilitates the movement of people in a structured and organized way; meets the country's labor needs; guarantees equal rights for Mexican natives and foreigners residing in the country; promotes family unity and socio-cultural integration; and facilitates the return and reintegration of Mexicans abroad.

The regulations and provisions of the law have not yet been drafted, and the legislation does not include details related to how the stated goals will be accomplished financially, administratively, or effectively.

Given a long track record of corruption within the country's immigration agency, the National Institute of Migration (INM), the challenges of a porous southern border, and the growing involvement of organized crime syndicates in human smuggling and human trafficking, many Mexican civil-society groups doubt the law will have much effect. In particular, critics argue that the law does little to limit the authority of INM agents who have been repeatedly accused of corruption and extortion of migrants. Others have criticized the law for responding only to immediate challenges and not taking a long-term view of Mexico's immigration policy needs. Absent such specifics, it is has been difficult for analysts to fully assess the legislation and its potential impact.